Liquid crystal flat displays, particularly Thin Film Transistor Liquid Crystal Displays (TFT-LCDs), are currently only display devices which catch up with or even surpass Cathode Ray Tubes (CRTs) in all directions in terms of overall performance such as brightness, contrast, power consumption, life, volume and weight etc. The liquid crystal flat displays have become the current mainstream display products due to excellent performance, good large-scale production characteristics, a high degree of automation, a low cost of raw materials, and a wide development space thereof.